Remember deopt-id -> context-level mappings in var descriptors.

runtime/vm/flow_graph_builder_test.cc

Index: runtime/vm/flow_graph_builder_test.cc
diff --git a/runtime/vm/flow_graph_builder_test.cc b/runtime/vm/flow_graph_builder_test.cc
index 74a8562b21e1a6c2777d8d6720efec41890f9bbd..b5c457d153c1d61579f3afe5d68e3fc562c72a78 100644
--- a/runtime/vm/flow_graph_builder_test.cc
+++ b/runtime/vm/flow_graph_builder_test.cc
@@ -60,8 +60,9 @@ class SourcePositionTest : public ValueObject {
         new ParsedFunction(thread_, Function::ZoneHandle(function.raw()));
     Parser::ParseFunction(parsed_function);
     parsed_function->AllocateVariables();
-    FlowGraphBuilder builder(*parsed_function, *ic_data_array, NULL,
-                             Compiler::kNoOSRDeoptId);
+    FlowGraphBuilder builder(*parsed_function, *ic_data_array,
+                             /* not building var desc */ NULL,
+                             /* not inlining */ NULL, Compiler::kNoOSRDeoptId);
     graph_ = builder.BuildGraph();
     EXPECT(graph_ != NULL);
     blocks_ = graph_->CodegenBlockOrder(optimized);